Bigger Brick...? Opinions, please...

Thinking about building a bigger Bolger Brick. Just a couple more
sheets of ply with careful scarfing and I'd have working pieces 12'
long. So a Brick about 11+ or so feet would emerge. Plan to keep her
4 foot beam, just lengthen somewhat.

Opinions on the following, please...

First, simply duplicating the existing curve of the bottom rocker
would make her a bit deeper, so I'm thinking of softening (i.e.
flattening the bottom rocker just a little. Any thoughts on the
adviseability/risk of that?

Second, with the added length, I could deck fore and aft and add
flotation underneath and enclose. Also have some secure stowage, and
still have at least a 4' x 8' "cockpit".

Third, I prefer a centerline spar. Thinking about mounting it at the
after end of the forward deck, more catboat style. How do we think
she'd do with a sprit sail? A lug? I also have a rig from an old
Super Snark in excellent condition -- a stripy lateen thing about 60
square feet. Big enough? Where should the center of effort go on that
boat (at her new length, that is). X% aft of the CG? Any guesses
that make sense?

Finally, would an aft skeg make sense? Might help her track better.
Here's a weird idea -- what about a box keel right about where an aft
skeg would go, about 18" wide. My thinking (or lack of it!!!) suggests
that such a structure wouldn't much impede her ability to sail, but
might just be enough of a surface to let her plane with an outboard on
her stern. Kind of a permanent trim tab. Well, I said it was weird...

Would appreciate constructive criticism. I get enough of the other
from my wife.

Thanks IA.